Gold And Graphite Deposits Prospecting In Bayan Obo Rift,Inner Mongolia

As an important part of the northern margin rift system of the North China Block,the Bayan Obo rift gets an unique continental margin tectonic environment and a long geological evolution that brings an enrichment of mineral resources.This area also cultivates many famous deposits like the giant Bayan Obo Fe-REE deposit and the large Haoyaoerhudong gold deposit.Relying on the program of “Special Geological Mapping and Technology Demonstration in Haoyaoerhudong-Saiwusu Integrated Prospecting area,Inner Mongolia”,this article mainly focuses on two typical deposits,the Dawudian graphite deposit and the Haoyaoerhudong gold deposit.Meanwhile,the corresponding mineral prediction models have been proposed to facilitate the prospection study using the integrated information.This article mainly dissects this following contents and achievements:(1)The geological evolution history of whole Lanshan-Jaertai-Bayan Obo rift in the northern margin rift system of North China Block is untangled systematically.Related metallogenic processes,metallogenic formations,as well as different types and relationships of the developed deposits are further discussed.(2)Combining the deposit geological features with the graphite analysis methods like Electronic Microscope\Scan Electronic Microscope,Raman Spectrum,X-ray Diffraction and Carbon Isotope,a thermal contact metamorphism genesis is expounded in the typical deposit researches of Dawudian crystal graphite deposit.The corresponding contact metamorphic phase can reach hornblende hornfels phase with the metamorphic temperature of 520-600? and pressure of 0.1-0.2GPa.The final graphitization of the low metamorphic carbonaceous strata in Bayan Obo Group is contributed by the late Variscan acidic magma.(3)The geological and geochemical characteristics of Haoyaoerhudong gold deposit is also investigated thoroughly.According to the morphological feature researches and LA-ICP-MS analysis of metal sulfides,this gold deposit is identified as a mesothermal-epithermal gold deposit and has a sedimentary-metamorphic genesis,in which the low metamorphic clastic wall rocks provide the main gold source and the late Hercynian acidic magmatism lead to the final mineralization.(4)In accordance with the researches of regional metallogenic theories and typical deposits,the prospecting geological models of Dawudian-type graphite deposit and Haoyaoerhudong-type gold deposit are put forward.Through the data processes of special maps and deposits prospecting using comprehensive information analysis methods like weights of evidence,neural net,more than 1000 wt predicted resources of crystal graphite has been discovered and verified in the study area.